I wouldn't worry too much, this could be the shock that this team needed. It's certainly not the first time this has happened. Under SAF I remember you lot losing 4-1 to Middlesbrough and Keane going nuts afterwards blaming Ferdinand, saying the attitude wasn't right and everyone thought they were a superstar, you went on to win a whole load of games of the back of it including beating Chelsea.
For what it's worth, I thought Pogba's reaction was good, he didn't try and blame anyone else and he admitted it was an appalling performance. Seems a mature response to me and given his words after Leicester he could have gone off the deep end, but he didn't.
Mou was the same made it all about collective blame, again could have gone off the deep end but didn't.
Losing is never good news, but this could be what is needed and with Sanchez coming back in and possibly Herrera, things can turn around very quickly.
From my point of view, you wont suffer long term from losing 3 points here, but for us a Brighton, these could be the biggest 3 points of the season!